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	$191.46	8.295%	$207.3416	$207.34	$207.35	$207.30
Purchase #2	$226.34	5.362%	$238.4764	$238.48	$238.50	$238.50
Purchase #3	$42.45	5.118%	$44.6226	$44.62	$44.60	$44.60
Purchase #4	$86.33	3.287%	$89.1677	$89.17	$89.15	$89.20
Purchase #5	$237.43	13.304%	$269.0177	$269.02	$269.00	$269.00
Purchase #6	$152.54	8.410%	$165.3686	$165.37	$165.35	$165.40
Purchase #7	$145.71	5.797%	$154.1568	$154.16	$154.15	$154.20
7 purchase totals =	$1,082.26		$1,168.1514	$1,168.16	$1,168.10	$1,168.20