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	$192.29	10.116%	$211.7421	$211.74	$211.75	$211.70
Purchase #2	$45.49	11.109%	$50.5435	$50.54	$50.55	$50.50
Purchase #3	$92.31	6.489%	$98.3	$98.30	$98.30	$98.30
Purchase #4	$221.59	10.814%	$245.5527	$245.55	$245.55	$245.60
Purchase #5	$80.83	10.306%	$89.1603	$89.16	$89.15	$89.20
Purchase #6	$205.43	13.770%	$233.7177	$233.72	$233.70	$233.70
Purchase #7	$71.92	10.655%	$79.5831	$79.58	$79.60	$79.60
7 purchase totals =	$909.86		$1,008.5994	$1,008.59	$1,008.60	$1,008.60