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	$200.56	5.359%	$211.308	$211.31	$211.30	$211.30
Purchase #2	$56.87	5.761%	$60.1463	$60.15	$60.15	$60.10
Purchase #3	$168.69	9.292%	$184.3647	$184.36	$184.35	$184.40
Purchase #4	$62.74	13.790%	$71.3918	$71.39	$71.40	$71.40
Purchase #5	$207.82	12.175%	$233.1221	$233.12	$233.10	$233.10
Purchase #6	$114.72	13.471%	$130.1739	$130.17	$130.15	$130.20
Purchase #7	$176.48	6.691%	$188.2883	$188.29	$188.30	$188.30
7 purchase totals =	$987.88		$1,078.7951	$1,078.79	$1,078.75	$1,078.80