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	$45.83	8.167%	$49.5729	$49.57	$49.55	$49.60
Purchase #2	$93.45	6.672%	$99.685	$99.69	$99.70	$99.70
Purchase #3	$221.72	10.258%	$244.464	$244.46	$244.45	$244.50
Purchase #4	$210.45	5.429%	$221.8753	$221.88	$221.90	$221.90
Purchase #5	$219.71	10.283%	$242.3028	$242.30	$242.30	$242.30
Purchase #6	$183.65	10.757%	$203.4052	$203.41	$203.40	$203.40
Purchase #7	$45.58	9.108%	$49.7314	$49.73	$49.75	$49.70
7 purchase totals =	$1,020.39		$1,111.0366	$1,111.04	$1,111.05	$1,111.10