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	$239.78	10.196%	$264.228	$264.23	$264.25	$264.20
Purchase #2	$86.94	10.805%	$96.3339	$96.33	$96.35	$96.30
Purchase #3	$223.29	4.675%	$233.7288	$233.73	$233.75	$233.70
Purchase #4	$60.66	4.860%	$63.6081	$63.61	$63.60	$63.60
Purchase #5	$60.86	11.533%	$67.879	$67.88	$67.90	$67.90
Purchase #6	$172.98	5.408%	$182.3348	$182.33	$182.35	$182.30
Purchase #7	$190.39	11.386%	$212.0678	$212.07	$212.05	$212.10
7 purchase totals =	$1,034.90		$1,120.1804	$1,120.18	$1,120.25	$1,120.10