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	$210.58	4.388%	$219.8203	$219.82	$219.80	$219.80
Purchase #2	$55.42	6.639%	$59.0993	$59.10	$59.10	$59.10
Purchase #3	$240.60	6.301%	$255.7602	$255.76	$255.75	$255.80
Purchase #4	$196.48	7.446%	$211.1099	$211.11	$211.10	$211.10
Purchase #5	$43.78	4.148%	$45.596	$45.60	$45.60	$45.60
Purchase #6	$228.59	11.346%	$254.5258	$254.53	$254.55	$254.50
Purchase #7	$142.41	5.817%	$150.694	$150.69	$150.70	$150.70
7 purchase totals =	$1,117.86		$1,196.6055	$1,196.61	$1,196.60	$1,196.60