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	$58.60	7.201%	$62.8198	$62.82	$62.80	$62.80
Purchase #2	$37.33	4.122%	$38.8687	$38.87	$38.85	$38.90
Purchase #3	$242.48	13.832%	$276.0198	$276.02	$276.00	$276.00
Purchase #4	$243.25	7.705%	$261.9924	$261.99	$262.00	$262.00
Purchase #5	$165.55	11.283%	$184.229	$184.23	$184.25	$184.20
Purchase #6	$50.29	7.139%	$53.8802	$53.88	$53.90	$53.90
Purchase #7	$225.33	11.206%	$250.5805	$250.58	$250.60	$250.60
7 purchase totals =	$1,022.83		$1,128.3904	$1,128.39	$1,128.40	$1,128.40