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	$184.31	3.719%	$191.1645	$191.16	$191.15	$191.20
Purchase #2	$196.44	11.657%	$219.339	$219.34	$219.35	$219.30
Purchase #3	$93.53	8.320%	$101.3117	$101.31	$101.30	$101.30
Purchase #4	$134.82	7.627%	$145.1027	$145.10	$145.10	$145.10
Purchase #5	$178.43	5.831%	$188.8343	$188.83	$188.85	$188.80
Purchase #6	$213.47	6.525%	$227.3989	$227.40	$227.40	$227.40
Purchase #7	$43.28	5.769%	$45.7768	$45.78	$45.80	$45.80
7 purchase totals =	$1,044.28		$1,118.9279	$1,118.92	$1,118.95	$1,118.90