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	$181.80	4.581%	$190.1283	$190.13	$190.15	$190.10
Purchase #2	$217.43	13.611%	$247.0244	$247.02	$247.00	$247.00
Purchase #3	$81.70	4.187%	$85.1208	$85.12	$85.10	$85.10
Purchase #4	$182.38	5.120%	$191.7179	$191.72	$191.70	$191.70
Purchase #5	$114.45	13.795%	$130.2384	$130.24	$130.25	$130.20
Purchase #6	$204.69	6.295%	$217.5752	$217.58	$217.60	$217.60
Purchase #7	$49.33	11.709%	$55.106	$55.11	$55.10	$55.10
7 purchase totals =	$1,031.78		$1,116.9110	$1,116.92	$1,116.90	$1,116.80