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	$211.48	10.283%	$233.2265	$233.23	$233.25	$233.20
Purchase #2	$194.57	12.414%	$218.7239	$218.72	$218.70	$218.70
Purchase #3	$149.92	4.152%	$156.1447	$156.14	$156.15	$156.10
Purchase #4	$53.73	8.544%	$58.3207	$58.32	$58.30	$58.30
Purchase #5	$93.90	6.147%	$99.672	$99.67	$99.65	$99.70
Purchase #6	$146.35	6.694%	$156.1467	$156.15	$156.15	$156.10
Purchase #7	$106.26	5.438%	$112.0384	$112.04	$112.05	$112.00
7 purchase totals =	$956.21		$1,034.2729	$1,034.27	$1,034.25	$1,034.10