Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$174.56	6.370%	$185.6795	$185.68	$185.70	$185.70
Purchase #2	$114.47	4.187%	$119.2629	$119.26	$119.25	$119.30
Purchase #3	$160.38	13.632%	$182.243	$182.24	$182.25	$182.20
Purchase #4	$183.38	5.840%	$194.0894	$194.09	$194.10	$194.10
Purchase #5	$135.52	9.855%	$148.8755	$148.88	$148.90	$148.90
Purchase #6	$170.41	5.132%	$179.1554	$179.16	$179.15	$179.20
Purchase #7	$129.63	9.133%	$141.4691	$141.47	$141.45	$141.50
7 purchase totals =	$1,068.35		$1,150.7748	$1,150.78	$1,150.80	$1,150.90