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	$210.86	8.605%	$229.0045	$229.00	$229.00	$229.00
Purchase #2	$13.54	9.689%	$14.8519	$14.85	$14.85	$14.90
Purchase #3	$50.94	5.132%	$53.5542	$53.55	$53.55	$53.60
Purchase #4	$179.69	9.573%	$196.8917	$196.89	$196.90	$196.90
Purchase #5	$98.34	13.215%	$111.3356	$111.34	$111.35	$111.30
Purchase #6	$199.66	12.420%	$224.4578	$224.46	$224.45	$224.50
Purchase #7	$197.72	11.862%	$221.1735	$221.17	$221.15	$221.20
7 purchase totals =	$950.75		$1,051.2692	$1,051.26	$1,051.25	$1,051.40