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	$141.61	6.706%	$151.1064	$151.11	$151.10	$151.10
Purchase #2	$72.89	13.229%	$82.5326	$82.53	$82.55	$82.50
Purchase #3	$94.58	7.120%	$101.3141	$101.31	$101.30	$101.30
Purchase #4	$120.99	5.458%	$127.5936	$127.59	$127.60	$127.60
Purchase #5	$238.31	3.323%	$246.229	$246.23	$246.25	$246.20
Purchase #6	$114.95	8.385%	$124.5886	$124.59	$124.60	$124.60
Purchase #7	$174.82	8.541%	$189.7514	$189.75	$189.75	$189.80
7 purchase totals =	$958.15		$1,023.1157	$1,023.11	$1,023.15	$1,023.10