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	$200.88	5.217%	$211.3599	$211.36	$211.35	$211.40
Purchase #2	$27.28	5.423%	$28.7594	$28.76	$28.75	$28.80
Purchase #3	$25.69	13.503%	$29.1589	$29.16	$29.15	$29.20
Purchase #4	$84.65	6.665%	$90.2919	$90.29	$90.30	$90.30
Purchase #5	$77.73	11.658%	$86.7918	$86.79	$86.80	$86.80
Purchase #6	$213.56	13.333%	$242.034	$242.03	$242.05	$242.00
Purchase #7	$169.48	9.682%	$185.8891	$185.89	$185.90	$185.90
7 purchase totals =	$799.27		$874.2850	$874.28	$874.30	$874.40