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	$188.69	10.765%	$209.0025	$209.00	$209.00	$209.00
Purchase #2	$112.53	10.854%	$124.744	$124.74	$124.75	$124.70
Purchase #3	$162.92	13.650%	$185.1586	$185.16	$185.15	$185.20
Purchase #4	$104.29	4.871%	$109.37	$109.37	$109.35	$109.40
Purchase #5	$204.63	10.135%	$225.3693	$225.37	$225.35	$225.40
Purchase #6	$151.27	13.570%	$171.7973	$171.80	$171.80	$171.80
Purchase #7	$86.28	7.593%	$92.8312	$92.83	$92.85	$92.80
7 purchase totals =	$1,010.61		$1,118.2729	$1,118.27	$1,118.25	$1,118.30